1. Field
One embodiment of the invention relates to a noise reduction apparatus and a noise reduction method suitably applied to an image signal processing system in a digital TV broadcasting receiver.
2. Description of the Related Art
As is known, in recent years, digitization of TV broadcasting has been promoted. For example, in Japan, not only satellite digital broadcasting such as BS (broadcasting satellite) digital broadcasting and 110-degree CS (communication satellite) digital broadcasting, but also terrestrial digital broadcasting has been started.
In such digital television broadcasting, an HD (high definition) type image signal having a high spatial frequency and ensuring a high quality image and a image signal having a low spatial frequency obtained by upconverting an SD (standard definition) type image signal providing a standard quality image are used in a mixed manner.
A frequency band containing a noise component differs between the image signal having a high spatial frequency and image signal having a low spatial frequency. Thus, when noise reduction processing is applied to a received image signal in a digital TV broadcasting receiver that receives such type of digital TV broadcasting, it is necessary to take into consideration the fact that a frequency band containing a noise component differs between image signals having different spatial frequencies.
Jpn. Pat. Appln. Publication No. 2004-096628 discloses a cyclic-type noise reduction apparatus. When controlling a feedback amount based on a movement amount detection signal obtained for each divided frequency band, the noise reduction apparatus adjusts a movement amount detection signal on the high frequency side using a movement amount detection signal on the lowermost frequency side to thereby improve an afterimage reduction effect at the high frequency region.